Kuttolamadom, Mathew, "Prediction of the Wear & Evolution of Cutting Tools in a Carbide / Ti-6Al-4V Machining Tribosystem by Volumetric Tool Wear Characterization & Modeling" (2012). All Dissertations. 1003. https://open.clemson.edu/all_dissertations/1003

The objective of this research work is to create a comprehensive microstructural wear mechanism-based predictive model of tool wear in the tungsten carbide / Ti-6Al-4V machining tribosystem, and to develop a new topology characterization method for worn cutting tools in order to validate the model predictions. This is accomplished by blending first principle wear mechanism models using a weighting scheme derived from scanning electron microscopy (SEM) imaging and energy dispersive x-ray spectroscopy (EDS) analysis of tools worn under different operational conditions. In addition, the topology of worn tools is characterized through scanning by white light interferometry (WLI), and then application of an algorithm to stitch and solidify data sets to calculate the volume of the tool worn away. The motivation for this work is two-fold. First, the evolving dominance of different wear mechanisms with time, as well as with significant tool and process factors has been characterized only in a limited fashion for this tribosystem. Traditional modeling of tool wear treats wear mechanisms individually. Hence, quantifying the mechanism-dominance at different operational conditions through a comprehensive approach of combining and weighting wear mechanisms is essential for understanding wear. Second is the critical need for better quantifying the wear itself. Wear is a 3D phenomenon. However, machining tool wear has historically been measured only in 1D which is inadequate to capture the true tool wear status, even with standardization. The methodology was to first combine and weight dominant microstructural wear mechanism models, to be able to effectively predict the tool volume worn away. Then, by developing a new metrology method for accurately quantifying the bulk-3D wear, the model-predicted wear was validated against worn tool volumes obtained from corresponding machining experiments. The changing dominance of different microstructural wear mechanisms was captured by formulating mechanism-weighting-factors from SEM imaging and EDS analysis. These were formulated for each of the three speed-regimes, which then fed into a multi-mechanistic volumetric wear rate model. On comparing this model-predicted wear to the actual tool volume worn away, prediction on the order of the observed wear was achieved, with better prediction at low and medium surface speeds - this was quantified by sum-of-squares computations. On analyzing worn crater faces using SEM/EDS, adhesion was found dominant at lower surface speeds, while dissolution wear dominated with increasing speeds - this is in conformance with the lower relative surface speed requirement for micro welds to form and rupture, essentially defining the mechanical load limit of the tool material. It also conforms to the known dominance of high temperature-controlled wear mechanisms with increasing surface speed, which is known to exponentially increase temperatures especially when machining Ti-6Al-4V due to its low thermal conductivity. Thus, straight tungsten carbide wear when machining Ti-6Al-4V is mechanically-driven at low surface speeds and thermally-driven at high surface speeds. Further, at high surface speeds, craters were formed due to carbon diffusing to the tool surface and being carried away by the rubbing action of the chips - this left behind a smooth crater surface predominantly of tungsten and cobalt as observed from EDS analysis. Also, at high surface speeds, carbon from the tool was found diffused into the adhered titanium layer to form a titanium carbide (TiC) boundary layer - this was observed as instances of TiC build-up on the tool edge from EDS analysis. A complex wear mechanism interaction was thus observed, i.e., titanium adhered on top of an earlier worn out crater trough, additional carbon diffused into this adhered titanium layer to create a more stable boundary layer (which could limit diffusion-rates on saturation), and then all were further worn away by dissolution wear as temperatures increased. At low and medium feeds, notch discoloration was observed - this was detected to be carbon from EDS analysis, suggesting that it was deposited from the edges of the passing chips. Mapping the dominant wear mechanisms showed the increasing dominance of dissolution wear relative to adhesion, with increasing grain size - this is because a 13% larger sub-micron grain results in a larger surface area of cobalt exposed to chemical action. On the macro-scale, wear quantification through topology characterization elevated wear from a 1D to 3D concept. From investigation, a second order dependence of volumetric tool wear (VTW) and VTW rate with the material removal rate (MRR) emerged, suggesting that MRR is a more consistent wear-controlling factor instead of the traditionally used cutting speed. A predictive model for VTW was developed which showed its exponential dependence with workpiece stock volume removed. Also, both VTW and VTW rate were found to be dependent on the accumulated cumulative wear on the tool. Further, a ratio metric of stock material removed to tool volume lost is now possible as a tool efficiency quantifier and energy-based productivity parameter, which was found to inversely depend on MRR - this led to a more comprehensive tool wear definition based on cutting tool efficiency.

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I had previously been doing all my slab flattening on a home made sled. It worked ok and it got the job done, but it had many limitations, some of which I didn't even realize until I started using the SpeTool sled. The first issue was that it had too much flex in the wood rails and would sag when I tried flatting slabs larger than about 20" wide. The second issue was the mess it made in the shop. It was actually so bad that I would have to use it outside. The biggest draw back however, wasn't realized until I started using the SpeTool sled. With the SpeTool sled I was able to work the router with the grain down the long side of the Slab This was something that I couldn't really do with my homemade sled. Working with the grain produces a smoother surface and is less work in my opinion. Then when you add in the dust collection, I was able to work in my shop again. Now I am not going to say you won't need to vacuum when you are done, but the mess is drastically less than with no dust collection. Also, the aluminum rails are much stiffer than my wood ones and don't flex nearly as much over larger spans. I would absolutely put this kit at the top of my list if I was setting a small garage shop up for slab flattening. Rob @ RM Woodcraft llc

Only having used this tool a couple of times, I am completely satisfied with it's performance. I have used the bit to flush trim a few patterns in walnut and white oak. This bit moved right through the wood. The cut was very smooth. I am also happy that I will be able to turn / swap out the cutters.

This is an investment! That being said, if you only doing one slab, I would recommend DIY build or having someone professionally flatten your project. I would hazard a guess that you would be saving for a fifth of the cost of this rig. I bought the dust shield with vacuum hose attachment and was disappointed on a few levels. Firstly, it's a gimmick that falls short of its intended purpose and although it may cut down a little of the waste being scattered in the shop, it does not work as advertised. Do your slab flattening outside or you'llbe vacuuming for days. Secondly the hose port fit is not standard for any shop vac, so you'll be needing some type of adapter. As for the router sled itself, the build is sturdy, and it does work as intended. However there is the minimal clearance issue. Even at its lowest setting, I still had to raise the work piece as the plunge depth of routers are limited. Also expect to clear debris (constantly) from wheel path as it collects and will hinder the smoorh and level tracking of the wheels Overall, it works. But I'm thinking I should have opted for the bearing rail system. I gave it 3 stars because that's where it falls in the overall rating. Average! These are my opinions from my experience. Your millage may vary. If I could send it back without the hassle. I probably would. I don't have the box, and the return policy says everything has to be in original unused condition, which is impossible after use.

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